
THE LIFE HISTORY ОЕ FERNS II 
change of environment, however, involves more than a mere 
change of form and texture. The foliage in the water requires no 
support; it simply floats, and it is probable that at first the 




Fig. 3.—Developed Prothallus, Antheridia, and Antherozoids. 
modified land plants got over this difficulty by being merely adherent 
to surfaces, as is still the case with our Marchantias, or Liverworts, 
and Lichens of to-day. The next thing, however, was the evolution 

